Heat-shrinkable uhmv polymer film, tubing, and roll covers

ABSTRACT

PTFE and other ultra high melt viscosity (UHMV) polymeric materials, such as TFM, and UHMW polyethylene are used, rather than FEP or PFA, in the HST process as it has been found that UHMV polymers may be readily substituted for FEP in the HST process with little significant change in the existing process steps. Appropriate expansion of a PTFE tube, after fabricating to the proper dimensions, may be obtained with pressure and heat treatment at a temperature of the order of 200° F., rather than 600-700° F. and the resulting tube is sufficiently stable to be shipped for later shrink application at comparable temperatures onto a roll at a mill. The resulting roll cover has improved mechanical properties at high temperatures and man be reinforced with a conductive additive for providing anti-static qualities or other additives to improve its wear and compressive strength. Also, the UHMV polymers may be processed in the form of film to produce improved heat-shrinkable film that is shrinkable at comparatively low temperatures and particularly heretofore unrealized UHMWPE heat-shrinkable film

CLAIM OF PRIORITY BASED ON CO-PENDING PROVISIONAL APPLICATION

[0001] The present application is related to co-pending Provisionalpatent application U.S. Ser. No. 60/019,438 of Frank M. and Randall F.Chapman, filed Jun. 10, 1996, entitled “HEAT-SHRINKABLE UHMV POLYMERFILM, TUBING, AND ROLL COVERS”, and based on which priority is herewithclaimed under 35 U.S.C. 119(e), and any other applicable statute orConvention, and the disclosure of which is incorporated herein byreference in its entirety.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates generally to the production ofheat-shrinkable thermoplastic material and to the fabrication of films,sheets, and tubing of such material, as well as roll covers used onmachinery rollers, such as paper machine rolls, textile rolls, foodprocessing rolls, and lamination equipment.

[0004] 2. Prior Art

[0005] Heat-shrinkable thermoplastics are used in many applications,among which are covering for machinery rollers in mill installations,such as in paper mills, where the rolls are used for guiding, spreading,and carrying the material being processed. These rolls are commonlyprovided with a polymer cover on their surface to resist corrosion andminimize friction and sticking. Various processes and materials formaking and applying such tubes and roll covers are disclosed in U.S.Pat. No. 3,050,786 to A. N. St. John et al, U.S. Pat. No. 3,225,129 toJ. S. Taylor et al, U.S. Pat. No. 3,426,119 to F. M. Chapman et al, U.S.Pat. No. 3,481,805 to R. L. Holmes et al, U.S. Pat. No. 3,749,621 to J.P. Shoffner, U.S. Pat. No. 4,325,998 to H. S. Chapman, and U.S. Pat. No.5,142,759 to J. Bonander et al.

[0006] A typical polymer cover of this type is in the form ofHeat-Shrinkable Tubing (HST) commonly made from fluorinatedethylene-propylene copolymer (FEP), and less often from perfluoroalkoxy(PFA), a copolymer of tetrafluoroethylene (TFE) and perfluoropropylvinyl ether (PPVE). The HST is presently fabricated by taking a suitabletube, welded from FEP sheet or fabricated by some other method, andapplying pressure and heat to expand it hot, followed by cooling it inits expanded state to freeze the stress put into it by the expanding.The cooled tube is then shrunk onto the surface of the roll, again usingthe application of heat, to tightly shrink the tube or sleeve about thesurface. The heating temperatures used with FEP HST are typically in therange of 170° F. to 300° F., well below its melt temperature of about500° F.

[0007] The melt processable FEP and PFA that are typically used in theHST application have been chosen over polytetraflurorethylene (PTFE), orother ultra high melt viscosity (UHMV) fluoropolymers, such aschemically modified PTFE, available as “Hostaflon” from Hoechst AG ofBurgkirchen, Germany, and commonly referred to as TFM, even though thelatter materials have lower cost, greater strength, hardness, flex life,and other preferred physical properties and higher temperature use andservice limits. This choice has been primarily due to the understandingand expectation in the art that the latter materials require highertemperatures to shrink. UHMV polymers are polymers that have a meltviscosity, which is too high for conventional thermoplastic processing,being of the order of a million times higher than conventional polymersthat are suitable for melt processing. For example, PTFE has a meltviscosity of 10¹¹ poises while FEP has a melt viscosity of 10⁴ to 10⁵poises. Another UHMV polymer that has not been used in the HSTapplication is ultra high molecular weight polyethylene or UHMWPE, whichis an extremely high density polyethylene with a molecular weight rangeof 3,000,000 to 6,000,000. This compares with a molecular weight rangeof 300,000 to 500,000 for high molecular weight polyethylene (HMWPE),which can be readily melt processed. Again, the melt viscosity of UHMWPEis too high for conventional melt processing. Thus, while PTFE and otherUHMV polymers have many superior qualities and, in addition, may be muchless costly, still heretofore, FEP has been regarded as the preferredmaterial in implementing this shrink technique.

[0008] Expanded UHMV polymer tubes such as those made from PTFE areknown, but they have not been satisfactorily employed in the HST shrinkprocess since state of the art HST made from PTFE is typically heated tonear or above the gel temperature of PTFE, 621° F., first for expansionand again, after cooling, to effect complete recovery, i.e., shrinkageof the tube onto the roll. These temperatures are so high as to pose adanger of causing thermal damage to the substrate roll and as apractical matter they cannot be easily accomplished on larger sampleswith the application of energy from a simple tool, such as a hot air guncurrently used with FEP HST. Moreover, during heating of the HST to thegel temperature for recovery there is a tendency for one section of thetube to be overheated while the remainder of the tube is too cool toshrink on the roll. This leads to the problem of non-uniformrecovery/shrinkage of the tube. Although in the above-noted U.S. Pat.No. 3,050,786 it is taught that PTFE recovery can be accomplished atlower temperatures, as low as 300° F., this is at the expense of processtime, particularly when rapid cooling is used.

[0009] Problem to be Solved

[0010] Developing a system and method for producing heat-shrinkablefilm, sheets, and tubing with optimal properties and ease of processingand installation for facilitating use such as in making HST and in othersuitable applications.

[0011] Objects

[0012] It is accordingly an object of the present invention to utilizethe discovery that a conventional material, having heretoforeunappreciated capabilities, can be fabricated with a comparativelysimple process to achieve improved heat-shrinkable film, tubing, androll covers.

[0013] It is another object of the present invention to reveal thesuperiority of PTFE, and other UHMV polymeric materials such as TFM, andUHMW polyethylene, over FEP and irradiated HMWPE in the heat-shrinkabletubing (HST) process for covering machine rolls and other components.

[0014] It is a further object of the invention to provide improvedheat-shrinkable tubes of TFE, TFM, and UHMWPE materials, reinforced withconductive and other additives, as covers for rolls, bars, tubes, pipes,and other elements of a relatively constant circumference, as well asimproved heat-shrinkable sheets and film of these materials,particularly heretofore unrealized UHMWPE heat-shrinkable film.

SUMMARY OF THE INVENTION

[0015] The present invention involves the discovery of the suitabilityand advantages to be achieved with the use of PTFE and other ultra highmelt viscosity (UHMV) polymers such as TFM, and UHMWPE, as heatshrinkable material, and their use, rather than FEP or PFA, in the HSTprocess. It has been found, for instance, that PTFE, typically fullysintered PTFE used in HST applications, may be readily substituted forPEP in the typical HST process with little significant change in theexisting process steps. Appropriate expansion of a PTEE tube may beobtained with pressure and heat treatment at temperatures less than 300°F., preferably in the range from about 190° F. to about 250° F., in amatter of a few minutes, and the resulting tube is sufficiently stableto be shipped for later shrink application at comparable temperaturesonto a roll at a mill. Also, UHMV polymers may be processed in the formof a sheet or a film to produce improved heat-shrinkable material thatis shrinkable at comparatively low temperatures in a minimum time,particularly heretofore unrealized UHMWPE heat-shrinkable film. The tubeand the sheet or film are shrinkable in at least one dimension and maybe shrinkable in two dimensions.

[0016] A typical HST process begins with the provision of a tube whichmay involve, first, cutting a sheet of ultra high melt viscosity (UHMV)polymer film, e.g., of PTFE, TFM, or UHMWPE, to the appropriatecircumference and length to fit the roll to be covered, as is done withFEP. The edges of the cut sheet are then joined, such as by fusionwelding, to form a tube with a seam that is strong enough to beexpanded. This tube is then expanded to a sufficient size to fit aboutthe surface of the roll, by closing its ends and placing it in anexpansion housing or sizing chamber, such as a cylindrical pipe thatwill accept the UHMV tube and determine the diameter to which it willexpand. The tube is expanded to that diameter using pressure and, ifdesired, heat, such as steam heat at a temperature of about 200° F., or,depending on the material thickness, to a temperature somewhere abovethe expansion temperature but below the gel temperature. The expandedtube is cooled to ambient temperature at the expanded diameter and issufficiently stable upon cooling to be stored for later shipment anduse. After shipment, the tube is slipped over the roll surface to becovered and, when positioned properly, the tube material is heated,e.g., using hot air guns, a gas torch, a heat blanket, or an oven, to atemperature sufficient to shrink it into tight contact with the surface,e.g., a temperature somewhat higher than the temperature at which it wasexpanded, typically at about 225° F. The shrink time is typically lessthan 3 minutes. The size of the circumference of the tube is choseninitially to be about 0.50 to about 0.95 times, and preferably fromabout 0.80 to about 0.92 times, the roll size. The resulting roll coverhas improved mechanical properties as well as being amenable to beingreinforced with suitable particulate additives such as a conductiveadditive to provide anti-static properties and additives to improve itswear, load carrying, and compressive strength, and to reduce its thermalexpansion, as are variously known in the art.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017]FIG. 1 is an illustrative diagram of an apparatus for expanding anUHMV polymer tube in accordance with the invention.

[0018]FIG. 2 illustrates a roll covered with an antistatic roll coverformed by a UHMV polymer tube that has been expanded by the apparatus ofFIG. 1, cooled to room temperature, and then heat shrunk about the roll.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] The present invention is based on the discovery that PTFE andother UHMV polymer materials, such as TFM, and UHMW polyethylene, can beutilized advantageously as heat-shrinkable material with heretoforeunappreciated ease and rapid, low temperature processing. A particularapplication is to use such UHMV polymer material, rather than FEP orPFA, in the conventional HST process, with minor modifications, toachieve a Heat-Shrinkable Tubing (HST) or roll cover of improvedqualities and economy. The UHMV polymers have been found to be suitablyshrinkable, after expansion, using a simple heating device, such as ahot air gun, for a few minutes at a comparable temperature to that ofthe FEP, e.g., significantly less than 300° F., rather than the 600-700°F. presently thought to be necessary by the art. Additionally, thiscapability may be exploited in producing improved heat-shrinkable sheetsand films of these materials.

[0020] In producing HST for roll covers, it has been discovered thattubes of PTFE and other UHMV polymers can be expanded under pressure,with or without heat, but preferably after mild heating, and then shrunkabout the surface of the roll again using mild heat to release thestresses therein. The tube is preferably heated before being expanded tobuild in adequate stresses to maintain the expansion upon cooling andwhich later are released by heat for shrinking the tube about the roll.Contrary to the prevailing belief in the art, the PTFE polymer tube neednot be heated to temperatures near the melting point when expanded inorder to achieve satisfactory stability upon cooling, and need not thenbe released at a comparable temperature to shrink about the roll.Rather, it has been found that heating the tube at temperaturescomparable to FEP processing, i.e., in the range from about 150° F. toabout 300° F., and preferably from about 190° F. to about 225° F.,before expanding the tube, will provide sufficient stresses in thematerial to give satisfactory stability upon cooling. The sufficientlystable expanded tube may be shrunk, immediately or later, about a rollsurface by releasing the stresses with the application of heat atcomparable temperatures, preferably somewhat higher than the expansiontemperature, e.g., about 225° F.-250° F. for a few minutes, typicallyless than 3 minutes.

[0021] It has also been determined that instead of processing the UHMVpolymer material in tubular form, it may be appropriately heated,expanded, and cooled as a sheet or film, so that, for example,heretofore unknown heat-shrinkable UHMWPE film may be produced that isshrinkable at easily workable temperatures. Further, unlike HMWPE, whichis irradiated to produce cross-linking to manufacture HST, the UHWPE maybe processed and heat shrunk without radiation. It also may beshrinkable in two dimensions.

[0022] An exemplary method for producing and applying an improvedheat-shrinkable covering material, such as for roll covers, or wirejacketing, or the like, in accordance with the invention is carried outgenerally as follows.

[0023] The cover is initially prepared by:

[0024] 1. First, a sheet of ultra high melt viscosity (UHMV) polymerfilm, e.g., of fully sintered PTFE, TFM, or UHMW polyethylene, is cut tothe appropriate circumference (somewhat smaller) and length (somewhatlonger) to fit the roll to be covered. Alternatively, paste extruded andsintered tubing or ram extruded tubing may be used rather than the film,in which event the next step is not required. Also, tape wrapping andsubsequent fusing is another commercial process for forming suitabletubing such as disclosed in the above-noted U.S. Pat. No. 3,225,129 toTaylor et al.

[0025] 2. The lengthwise edges of the cut sheet are then joined byfusion welding to form a tube with a seam that is strong enough to beexpanded.

[0026] 3. The fabricated tube, preparatory to being expanded to asufficient size to fit about the surface of the roll, is typicallyplaced in a pipe or similar expansion housing or chamber having avolumetric shape or diameter that will determine the size or diameter towhich the tube will expand.

[0027] 4. Both ends of the tube are then closed, for example, byinserting end plugs or plates therein, with holes for admitting anddraining fluids, and the ends are sealed with clamps that surround theends and plates.

[0028] 5. A differential pressure is applied so that the internalpressure in the tube causes the tube to expand, preferably after thetube has been heated to an elevated temperature of anywhere from about150° F. to about 300° F., preferably about 190° F. to about 225° F.

[0029] 6. The differential pressure is increased until the UHMV polymertube expands to fill the pipe or sizing chamber.

[0030] 7. The expanded and heated tube is then cooled down to ambienttemperature so as to freeze it at the expanded size. While the tube canbe expanded without the application of heat, its stability and internalstresses may be found unsatisfactory under such circumstances if thetube is not immediately placed on the roll or wire bundle. By heating tothe indicated temperatures before expansion, sufficient stability willbe produced to permit storage of the tube and later satisfactory releaseof the stresses and heat shrinking about the roll surface with the useof heat at similar temperatures.

[0031] 8. The pressure is held at a sufficient level during cool down toprevent the tube from shrinking from the expanded size.

[0032] 9. Cool down can be accelerated by spraying water on theexpansion pipe or sizing chamber or allowing slow cooling of the sleeveby air to achieve a sufficiently stable state at ambient temperature.

[0033] 10. The assembly is then dismantled and the expanded tuberemoved. The unexpanded end portions beyond the clamps may be cut off.The expanded tube is now ready for application to a roll immediately, orit may be stored in this sufficiently stable condition until selectedfor use. It may be shipped in this condition to the point ofapplication, e.g., a paper mill, and shrunk onto a roll at the mill. Itis believed that the sufficiently stable condition can be assured by andresults from the cooling in of the stress created within the material bythe pressurizing at an elevated temperature.

[0034] When the expanded tube is ready for application, then:

[0035] 11. The expanded UHMV polymer tube is slipped over the surface ofthe object to be covered, e.g., a machinery roller, or a wire bundle, inthe event it is to be used for jacketing on the bundle, or a coupling ona pipe to be joined.

[0036] 12. When positioned properly over the surface to be covered, theexpanded tube material is then heated again, e.g., using hot air guns, agas torch, an oven, or a heating blanket, to a temperature in generalsomewhat above the expansion temperature and definitely below its geltemperature and particularly, e.g., 225° F.- 250° F., to shrink it intotight contact with the surface. The heat shrinking temperature ispreferably somewhat higher than the expansion temperature and shrinkingshould normally take less than 3 minutes. Upon cooling of the material,the roll has been provided with an improved cover.

[0037] In addition to the foregoing exemplary general method offabricating and installing heat shrinkable covering material, aparticular example of a means and specific parameters for preparing andexpanding the tube in a roll cover fabricating method in accordance withthe invention involves the following.

[0038] 1. When a UHMV tube of fully sintered PTFE, for example, isinitially being fabricated, the size of the circumference of the tube ischosen to be about 0.50 to about 0.95, preferably about 0.80 to 0.92,times the roll size upon heating. The material may be reinforced withsuitable additives and particulates, such as carbon and other knownelectrically conductive additives to impart anti-static propertiesand/or other additives to enhance its load carrying and compressivestrength and wear resistance.

[0039] 2. As shown in FIG. 1, the tube 1, after fabrication, has one endclosed, for example the right end, by inserting therein an end plug orplate 2, having holes for respectively accommodating a conduit 6 foradmitting compressed air and a conduit 7 for admitting steam.Conveniently, the end plate 2 is of aluminum, with a ½″ top hole, foradmitting the compressed air, and a ½″ bottom hole, for admitting steam,aligned on the bottom.

[0040] 3. High torque hose clamps 3 are placed over the PTFE tubematerial 1 around the end plate 2 and torqued to about 160 inch-lbs. toseal the tube end. The maximum torque for the hose clamps is about170-180 inch-lbs.

[0041] 4. The other end of the tube 1 is also closed with an end plug orplate 2, conveniently of aluminum and having ½″ top hole, for checkingthe pressure in and venting the tube interior, and a ½″ bottom hole, foraccommodating a fluid drain 5 pipe, aligned on the bottom.

[0042] 5. High torque hose clamps 3 are similarly placed over the PTFEtube material around the latter end plate and torqued to 160 inch-lbs.

[0043] 6. A quick disconnect for the steam conduit 7 is attached to thebottom ½″ hole in the right end plate 2, and a ⅜″ compressed air line 6with a ball valve is inserted into the top hole.

[0044] 7. On the other end plate 2, a ½″×6′ long drain pipe 5 with ballvalve is inserted into the bottom hole and a quick disconnect with avalve on the same line 9 is attached to the upper hole running to a 30psi pressure gauge at a control panel.

[0045] 8. The UHMV tube or sleeve 1 is then inflated with air, makingsure that the drain line 5 is on the bottom and that the tube 1 isplaced at an angle that will let water drain out through the drain valvein pipe 5.

[0046] 9. Steam is admitted into the tube l through conduit 7 with thedrain and pressure release valves, in the lines 5 and 9 connected toleft end plate 2, open.

[0047] 10. The temperature is brought up to about 200° F.-205° F. whilemaintaining the pressure at a sufficient level to maintain the tubeinflated, e.g., about 2.5 psi.

[0048] 11. The pressure is then increased until the heated tube 1expands to fill the sizing chamber or expansion pipe 8.

[0049] 12. The pressure is held at the increased level to prevent thetube 1 from shrinking from the expanded size and the tube is then cooledin the expanded state. The expanded UHMV polymer or PTFE material, soprocessed, has been found to be sufficiently stable upon the completionof cooling. It is believed that this stability is the result of coolingin the stress created within the material by the heating andpressurizing.

[0050] 13. Cool down may be accomplished by spraying water on theexpansion housing or sizing chamber 8, or by allowing slow cooling ofthe tube 1 by air.

[0051] 14. The chamber 8 and tube end sealing assemblies and conduitsare then dismantled and the expanded PTFE tube removed in condition forapplication to a roll. It can be used immediately or it can be stored inthis stable condition until ready for application to a roll, whereuponit may be shipped to the point of use, e.g., a paper mill.

[0052] 15. When ready, as shown in FIG. 2, the tube 1 may then be shrunkonto a roll 20 by slipping it over the roll surface and heating again,e.g., using hot air or a heating blanket or such, to a temperaturecomparable to that at which it was expanded, e.g., in the range fromabout 190° F. to about 225° F., and typically somewhat higher than theexpansion temperature at about 225° F., for a few minites to shrink itinto tight contact with the roll surface.

[0053] 16. As seen in FIG. 2, the installed roll cover may have endportions 1 a extending beyond the ends of the roll 20, that have beencompletely shrunk down. These end portions are then cut off to completethe installation.

[0054] It will accordingly be seen that an improved roll cover may beachieved using PTFE, and other UHMV polymeric materials such as TFM, andUHMWPE, in place of FEP, in the conventional HST process, with minormodifications. These UHMV polymers produce a roll cover of improvedqualities and economy, which may also be enhanced or reinforced with aconductive additive to impart anti-static properties and/or otheradditives to enhance the load carrying and compressive strength and wearresistance. Further, the UHMV polymers may be processed so as to produceimproved heat-shrinkable films, such as of UHMWPE, that are shrinkableat comparatively low temperatures.

1. An article of manufacture comprising a UHMV polymer having a meltviscosity too high for conventional melt processing and with apressure-expanded shape in a stable stressed condition that is capableof heat-shrinking in at least one dimension under the application ofmild heating to release the stressed condition.
 2. The article of claim1 wherein said UHMV polymer is capable of heat-shrinking by being mildlyheated at a temperature below 300° F.
 3. The article of claim 1 whereinsaid UHMV polymer is capable of expansion to said pressure-expandedshape in a stable stressed condition by being initially heated at atemperature in the range from about 190° F. to about 250° F., beingexpanded under pressure to the pressure-expanded shape, and brought toambient temperature under pressure while maintaining thepressure-expanded shape whereby a sufficiently stable stressed conditionexpanded UHMV polymer article results that is capable of subsequent heatshrinking under the application of said mild heating to an approximateunexpanded shape.
 4. The article of claim 3 wherein saidpressure-expanded shape UHMV polymer article is capable of heatshrinking under mild heating at a temperature somewhat above saidinitially heated temperature.
 5. The article of claim 1 wherein saidUHMV polymer comprises a material selected from the group consisting offully sintered polytetraflurorethylene (PTFE), modifiedpolytetraflurorethylene (TFM), and UHMW polyethylene [(UHMWPE)].
 6. Thearticle of claim 1 wherein said pressure-expanded shape of said UHMWpolymer is a tube.
 7. The article of claim 6 further comprising a rolland wherein said tube is shrunk about and covers said roll.
 8. Thearticle of claim 7 wherein said roll covered by said tube is formed as amachinery roller.
 9. The article of claim 1 wherein saidpressure-expanded shape of said UHMW polymer is a sheet or film.
 10. Thearticle of claim 1 wherein said article is a film of UHMW polyethylene.11. The article of claim 1 containing an additive and wherein saidadditive comprises a material selected from the group consisting ofcarbon, material providing electrical conductivity, material providingimproved abrasion resistance, material providing improved wearresistance, material providing improved load carrying, materialproviding improved compressive strength, and material providing reducedthermal expansion to said shaped article, and combinations of saidmaterials.
 12. A process for producing an article of manufacturecomprising an article of an ultra-high melt viscosity (UHMV) polymerwhich is heat-shrinkable in at least one dimension under the applicationof mild heating to a desired shape, comprising the steps of: providing asupply of UHMV polymer; initially mildly heating said supply of UHMVpolymer; applying pressure to the heated supply to expand it generallyto the form of the desired shape; and bringing said expanded supply toambient temperature under pressure to maintain the expanded form of theshaped article and produce a sufficiently stable expanded UHMV polymerarticle capable of subsequent heat shrinking into the desired shape ofsaid article.
 13. The process of claim 12 wherein said supply of UHMVpolymer is initially heated at a temperature in the range from about190° F. to about 250° F.
 14. The process as in claim 13 wherein saidsufficiently stable expanded UHMV polymer article is mildly heated at atemperature somewhat above said initially heated temperature.
 15. Theprocess of claim 12 comprising the further step at heating saidsufficiently stable expanded UHMV polymer article at a mediumtemperature below about 250° F. to shrink it about an object.
 16. Aprocess for producing a heat-shrinkable tube (HST) useful as a rollcover comprising the steps of: providing a tube of UHMV polymer;inserting said tube into an expansion housing and heating said tube to atemperature below the gel temperature of said UHMV polymer; applyingpressure to the heated tube to expand its diameter to that of theinterior of the housing; and bringing said expanded diameter tube toambient temperature under pressure to maintain the expanded diameter andproduce a sufficiently stable expanded UHMV polymer tube capable ofsubsequent use as an HST roll cover by shrinking onto a roll with mildheating.
 17. A process as in claim 16 further comprising the steps of:placing said sufficiently stable expanded UHMV polymer tube about thesurface of a roll; and heating said tube to a mildly heating temperatureto shrink it into tight contact with said surface of said roll as a rollcover.
 18. The process of claim 16 wherein raid mildly heatingtemperature is in the range from about 190° F. to about 250° F.
 19. Aprocess as in claim 16 wherein said UHMV polymer comprises a materialselected from the group consisting of polytetraflurorethylene (PTFE),modified polytetraflurorethylene (TFM), and UHMW polyethylene (UHMWPE).20. A process as in claim 16 further comprising the step of reinforcingsaid UHMV polymer with an additive and wherein said additive comprises amaterial selected from the group consisting of an electricallyconductive additive, an abrasion resistance improving additive, a wearresistance improving additive, a load carrying improving additive, acompressive strength improving additive, carbon, and combinationsthereof.